BIOL 111 Lecture Notes - Lecture 46: Pulmonary Vein, Pulmonary Artery, Cellular Respiration

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23 Jul 2016
BIOL 111 Organismal Biology
73 of 89
!external: feathers or fur
!internal: fatty layers
o!cooling systems:
!sweat glands
!lots of food required
!about 90% of energy in the body is heat energy and is not used for
!lots of oxygen is required for cellular respiration
!efficient respiratory and circulatory system required
Birds’ Circulatory and Respiratory Systems
!birds have a four-chambered heart
o!this is similar to mammalian and crocodilian heart
!there is no mixing of blood
!deoxygenated blood enters the right atrium from the vena cava
!blood goes to the lungs from the right ventricle by the pulmonary artery
!oxygenated blood from the lungs enter the left atrium from the pulmonary vein
!blood is pumped to the body through the aorta from the left ventricle
!in the right atrium is the sinoatrial node (SA node/ pacemaker) which can stimulate an
action potential that controls the muscle contraction of the heart
!birds have a highly efficient respiratory system
o!flying and endothermy require lots of oxygen
o!system is much more complex and efficient than mammals
o!this allows some birds to fly at altitudes of 30000+ metres
!air flow is unidirectional (compare to tidal flow in mammals) in the birds’ lungs
o!they have a smaller lungs with 8-9 air sacs branching off anteriorly and
o!on inhalation, air is drawn through the trachea into the posterior air sacs
o!on exhalation, the air is propelled through the lungs
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